Field of the Invention
The present invention relates to a cleaning blade for use in an electrophotographic image forming apparatus, a process cartridge and an electrophotographic image forming apparatus.
Description of the Related Art
An electrophotographic image forming apparatus is conventionally equipped with a cleaning member of various types to remove toner remaining on an image bearing member after a transfer of a toner image from the image bearing member such as a photosensitive member onto an object to be transferred such as a paper and an intermediate transfer member. Among the cleaning members, a cleaning blade using a plate-shaped elastic member is well known. In particular, the elastic member is formed of polyurethane elastomer in many cases. In recent years, in accordance with improvement in the image quality of an electrophotographic image forming apparatus, spheronization of toner and micronization of toner have been progressed. Furthermore, in accordance with prolonging life of an electrophotographic image forming apparatus, the surface of an image bearing member such as photosensitive member is shaved to a deeper depth. Accordingly, the toner remaining on the image bearing member tends to slip through a cleaning blade easily. A cleaning blade is therefore required to have higher cleaning performance.
Examples of the method for improving the cleaning performance include a method for increasing the contact pressure of a cleaning blade against an image bearing member. When the method is employed, however, the increased friction force between the image bearing member and the cleaning blade causes unstable movement of the cleaning blade at the contact portion, with the generation of abnormal noise and turn-up of the cleaning blade in some cases.
Also, Japanese Patent Application Laid-Open No. 2001-75451 discloses a method for reducing the friction between an image bearing member and a cleaning blade by increasing the concentration of the isocyanurate group at the contact portion of the cleaning blade formed of polyurethane elastomer so as to increase the hardness of the contact portion. Further, Japanese Patent Application Laid-Open No. 2007-39678 discloses a method for imparting flexibility to the tip of a cleaning blade by addition of a polyether polymer, in the isocyanate treatment to increase the hardness of the contact portion.